Examples of an electronic component which requires hermetic enclosure include piezoelectric resonator devices, such as a crystal vibrator, a crystal filter, a crystal oscillator, and the like. In all of these piezoelectric resonator devices, a metal thin-film electrode is formed on a surface of a crystal resonator plate, and the crystal resonator plate is hermetically sealed to protect the metal thin-film electrode from the outside air. In these piezoelectric resonator devices, generally, due to requirement for surface mounting of components, a piezoelectric element (crystal resonator plate) is housed in a ceramic package (insulating package) and is covered with a metal lid on which a brazing material is formed, and the ceramic package and the metal lid are welded together to hermetically seal the piezoelectric vibrating element. As described in Patent Document 1, as there is a trend toward low-height and low-cost electronic-component containers, a type of electronic-component container in which the brazing material of the metal lid is directly welded to a metallized sealing portion formed on the ceramic package without via a metal sealing ring on the ceramic package (so-called direct seam sealing type, beam sealing type, etc.) is currently increasingly used.
Patent Document 1: JP 2003-168949 A